Flexible tether position tracking camera inspection system for visual inspection of off line industrial gas turbines and other power generation machinery

CROSS-REFERENCE TO RELATED APPLICATIONS

This application incorporates by reference the entire contents of each of co-pending U.S. patent applications:

“Flexible Linkage Camera System And Method For Visual Inspection Of Off Line Industrial Gas Turbines And Other Power Generation Machinery”, filed Aug. 21, 2013, Ser. No. 13/972,332, United States patent application publication number 2014/0055596;

“System And Method For Visual Inspection And 3D White Light Scanning Of Off-Line Industrial Gas Turbines And Other Power Generation Machinery”, filed Aug. 21, 2013, Ser. No. 13/97,200, United States patent application publication number 2013/0335530; and

“System And Method For Automated Optical Inspection Of Industrial Gas Turbines And Other Power Generation Machinery With Multi-Axis Inspection Scope”, filed Jan. 31, 2012, Ser. No. 13/362,352, United States patent application publication number 2013/0192353.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to optical camera systems for nondestructive internal inspection of power generation machinery, including by way of non-limiting example industrial gas and steam turbine engines as well as generators. More particularly aspects of the invention relate to a visible light or infra-red optical camera inspection system that is capable of positioning camera fields of view (FOV) through a gas turbine inspection port, inlet or outlet in any portion of the engine, including the compressor section, combustor nozzle and transition and turbine section, capturing visual images of the engine's internal structure. One or more cameras are mounted within a camera head that is translated to areas of interest within the turbine or other power generation machinery by a flexible tether, so that their respective fields of view capture desired images. The includes a camera head position system that inferentially determines three dimension (3D) position of the camera head, so that the captured images and their position are correlated for future analysis. In this manner images from any inspected position within the machinery can be selectively recalled for review or multiple images can be stitched to create a composite image of the machinery inspected areas.

2. Description of the Prior Art

Power generation machinery, such as steam or gas industrial turbines, are often operated continuously with scheduled inspection and maintenance periods, at which time the turbine is taken offline and shut down. By way of example, a gas turbine engine often will be operated to generate power continuously for approximately 4000 hours, thereupon it is taken off line for routine maintenance, inspection, and repair of any components identified during inspection. Taking a gas turbine off line and eventually shutting it down completely for scheduled maintenance is a multi-day project. Some turbine components, such as the turbine rotor section, are operated at temperatures exceeding 1000° C. (1832° F.). The turbine requires 48-72 hours of cooling time to achieve ambient temperature before complete shutdown in order to reduce likelihood of component warping or other deformation. During the shutdown phase the turbine rotor rotational speed is spooled down from operating speed of approximately 3600 RPM to a speed of approximately 120 RPM or less in “turning gear mode” where the rotor is externally driven by an auxiliary drive motor, in order to reduce likelihood of rotor warping. Other turbine components, such as the turbine housing, are also cooled slowly to ambient temperature.

Once the turbine is cooled to ambient temperature over the course of up to approximately 72 hours internal components of the now static turbine can be inspected with optical camera inspection systems. Known optical camera inspection systems employ rigid or flexible optical bore scopes that are inserted into inspection ports located about the turbine periphery. The bore scope is manually positioned so that its field of view encompasses an area of interest within the turbine, such as one or more vanes or blades, combustor baskets, etc. A camera optically coupled to the bore scope captures images of objects of interest within the field of view for remote visualization and archiving (if desired) by an inspector.

If a series of different images of different areas of interest within a given turbine inspection port are desired, the inspector must manually re-position the camera inspection system bore scope to achieve the desired relative alignment of internal area of interest and the field of view. Relative alignment can be achieved by physically moving the bore scope so that its viewing port is positioned proximal a static area of interest. Examples of such relative movement of bore scope and static turbine component are by inserting a bore scope in different orientations within a static combustor or radially in and out of space between a vane and blade row within the compressor or turbine sections. For rotating blade inspection, relative alignment can also be achieved by maintaining the bore scope viewing port in a static position and rotating the blade row blades successively into the camera static viewing field.

Previously referenced, commonly owned United States publication number 2013/0335530, entitled “System And Method For Visual Inspection And 3D White Light Scanning Of Off-Line Industrial Gas Turbines And Other Power Generation Machinery” and United States patent application publication number 2013/0192353, entitled “System And Method For Automated Optical Inspection Of Industrial Gas Turbines And Other Power Generation Machinery With Multi-Axis Inspection Scope” describes motorized inspection system embodiments that can be automatically maneuvered within power generation machinery or manually maneuvered under control of a human operator. Relative orientation coordinates of the driven motion axes are monitored by the system, so that the inspection camera head position and orientation are known by referencing those axes coordinates.

In other types of power generation machinery internal optical inspection procedures it is desirable to position manually under human operator control a camera head mounted on a flexible tether and record the camera images, as is described in previously referenced, commonly owned United States publication number 2014/0055596, entitled “Flexible Linkage Camera System And Method For Visual Inspection Of Off Line Industrial Gas Turbines And Other Power Generation Machinery”. For example, non-rotating static vane inspections within compressor or turbine section rows require physical movement of the inspection scope camera system field of view to each individual vane. The narrow confines of passages surrounding stationary vanes often will not facilitate passage of traditional inspection scope systems. In order to complete inspection of the vanes, supporting structures, such as vane shrouds are removed to provide sufficient visual exposure and/or passage of inspection scope components within the restricted confines of vane rows.

Thus, complete turbine inspection with a flexible, tethered camera inspection system, such as that described in United States publication number 2014/0055596, requires multiple manual relative repositioning sequences between the camera inspection system viewing ports and other internal inspection access points to allow complete visual inspection of all areas of interest within the turbine. Inspection apparatus positioning is challenging due to the complex, often tortuous manipulation paths between components in a gas turbine. The inspection scope camera delivery system must be sufficiently flexible to insert through tight confined passages, yet not too flexible or limp to prevent controlled positioning within the passages. Unlike the aforementioned motorized multi-axis inspection system that is described in United States patent application publication number 2013/0192353, the flexible tethered camera inspection system does not provide camera head position/orientation information that can be advantageously combined with the optical image information for future analysis or composite image generation.

SUMMARY OF THE INVENTION

Accordingly, a suggested object of the invention is to correlate flexible tethered camera inspection system camera head position with captured images, such as is possible with a motorized multi-axis camera inspection system.

This and other objects are achieved in one or more embodiments of the invention by a camera scope inspection system with a flexible tether mounted camera head and a camera head position sensing system that inferentially determines the three dimension (3D) position of the camera head. Camera head position data are correlated with camera image data by a controller. In this manner correlated internal inspection image data and corresponding position data are available for future analysis and image tracking similar to data processing performed with data gathered from multi-axis motorized inspection systems, with the advantages of being able to maneuver manually the tethered camera scope into confined spaces not readily accessible by the multi-axis systems.

Some embodiments of the invention feature a flexible, position tracking camera scope inspection system for internal inspection of power generation machinery. The system includes a camera scope with a flexible elongated tether, having a distal end adapted for insertion into a blind cavity of a rotating machine. A camera head is coupled to the tether distal end. An optical camera, having a field of view, is coupled to the camera head, for generating image data. A camera head position sensing system inferentially determines three dimension (3D) position of the camera head and generating inferred camera head position data. A controller is coupled to the camera scope optical camera and the camera head positioning system, for correlating the image and position data. Various embodiments of the positioning system include: (i) an inertial sensor, for correlating camera head movement with inferred camera head 3D position; (ii) a contactless remote position tracking system including a wireless positioning transmitter coupled to the camera head, for transmitting a positional signal and a wireless positioning system receiver for receiving the positional signal, locating the positioning transmitter's 3D position and correlating the positioning transmitter's located position with inferred camera head 3D position; (iii) a remote tether insertion depth sensing system including tether markers arrayed along the tether length and a transceiver coupled in proximity to a rotating machine cavity that is capable of detecting the markers, for correlating a detected marker with inferred camera head 3D position; and (iv) a tether flexure sensing system for correlating sensed tether flexure with inferred camera head 3D position. Some embodiments of the tether flexure sensing system comprises a sensing array coupled to the tether that correlates array distortion with tether flexure, such as a magnetic- or capacitance-based proximity sensor array.

Other embodiments of the invention feature a flexible, position tracking camera scope apparatus, comprising a flexible elongated tether, having a distal end adapted for insertion into a blind cavity of a rotating machine. A camera head is coupled to the tether distal end, which includes therein an optical camera, having a field of view, for generating image data. A camera head position sensing system inferentially determines three dimension (3D) position of the camera head and generates inferred camera head position data.

Additional embodiments of the invention feature a method for internal inspection of rotating machinery, by providing a flexible, position tracking camera scope inspection system. The inspection system includes a camera scope with a flexible elongated tether. The tether has a distal end adapted for insertion into a blind cavity of a rotating machine. A camera head is coupled to the tether distal end and incorporates an optical camera, having a field of view, coupled to the camera head, for generating image data. A camera head position sensing system inferentially determining three dimension (3D) position of the camera head and generates inferred camera head position data. A controller is coupled to the camera scope optical camera and the camera head positioning system, for correlating the image and position data. The featured method is performed by inserting the camera scope into a blind cavity of a power generation machine. The tether and camera head are maneuvered through the rotating machine cavity. The camera and position sensing system respectively capture image and position data. The controller correlates captured image and position data and uses the correlated data to generate an inspection data set. The inspection data set is available for analysis and image manipulation, including composite image generation.

The respective objects and features of the invention may be applied jointly or severally in any combination or sub-combination by those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which:

<figref idref="DRAWINGS">FIG. 1</figref> is a partial cross sectional schematic view of a gas turbine; that is being inspected with two exemplary camera scopes that incorporate embodiments of the invention;

<figref idref="DRAWINGS">FIG. 2</figref> is a fragmented plan view of a gas turbine engine turbine section showing positioning of an exemplary camera scope of the invention between successive vane and blade rows;

<figref idref="DRAWINGS">FIG. 3</figref> is a schematic view of a flexible, position tracking camera scope inspection system embodiment being used to perform an inspection within a gas turbine engine casing, wherein a remote tether insertion depth sensing system senses tether insertion L into the casing;

<figref idref="DRAWINGS">FIG. 4</figref> is a schematic view of a flexible, position tracking camera scope inspection system embodiment being used to perform an inspection within a gas turbine engine casing, wherein designated waypoint markings or objects in an inspected power generation machine viewed by the optical camera field of view are used to corroborate correlation of the image and camera position data by comparison with a previously validated correlation image and position data sets;

<figref idref="DRAWINGS">FIG. 5</figref> is a schematic view of an exemplary camera head embodiment of the invention;

<figref idref="DRAWINGS">FIG. 6</figref> is a schematic perspective view of an inspection scope tether embodiment of the invention that incorporates a tether flexure sensing system array of sensors oriented axially and radially about the tether circumference, for correlating sensed tether flexure with inferred camera head 3D position;

<figref idref="DRAWINGS">FIG. 7</figref> is a schematic perspective view of another inspection scope tether embodiment of the invention that incorporates a tether flexure sensing system helical array of sensors for correlating sensed tether flexure with inferred camera head 3D position;

<figref idref="DRAWINGS">FIG. 8</figref> is a schematic view of the sensor array embodiment of <figref idref="DRAWINGS">FIG. 6</figref> where the tether is in a straightened, axially extended orientation; and

<figref idref="DRAWINGS">FIG. 9</figref> a schematic view of the sensor array embodiment of <figref idref="DRAWINGS">FIG. 6</figref> where the tether is flexed.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.

DETAILED DESCRIPTION

After considering the following description, those skilled in the art will clearly realize that the teachings of the present invention can be readily utilized in a camera scope inspection system with a flexible, tether mounted camera head that is maneuverable in confined internal cavities of power generation machinery. A camera head position sensing system inferentially determines the three dimension (3D) position of the camera head within the inspected machinery. Camera head position data are correlated with camera image data by a controller. In this manner correlated internal inspection image data and corresponding position data are available for future analysis and image tracking.

Referring to <figref idref="DRAWINGS">FIGS. 1-3</figref>, embodiments of the invention facilitate automated off-line remote visual inspection of gas turbine <b>30</b> internal components, including the compressor section <b>32</b>, the combustor section <b>34</b>, the turbine section <b>38</b> Row 1 and Row 2 fixed vanes <b>42</b>, <b>46</b>; leading Row 1 and Row 2 rotating blades <b>44</b>, <b>48</b> that circumscribe the turbine shaft <b>40</b>; and ring segments. Embodiments of the present invention flexible tether camera inspection system enables inspection of offline turbines by introducing one or more remote, manually positioned and/or actuated optical camera inspection scopes <b>60</b> into one or more of the turbine inspection ports <b>36</b>, <b>50</b> and <b>52</b>, simultaneously or sequentially. Upon insertion of an inspection scope <b>60</b>, its tether <b>62</b> is selectively positioned manually by an operator or with assistance of an insertion drive mechanism (not shown). One or more cameras are mounted in camera head <b>70</b> and image data in each camera's field of view (FOV) are acquired, captured, and if desired archived for further analysis.

The inspection scope <b>60</b> is part of the position tracking inspection system <b>80</b> that also incorporates a camera head position sensing system for inferentially determining three dimension (3D) position of the camera head <b>70</b> and for generating inferred camera head position data. Exemplary embodiments of camera head positioning systems are shown in <figref idref="DRAWINGS">FIG. 3</figref>. Inspection system controller <b>82</b> is coupled to the camera scope optical camera, in order to receive and process image data, such as is described in the aforementioned United States patent application publications numbers 2013/0335530 and 2013/019235. The controller <b>82</b> is also coupled to the camera head positioning system, for receiving and processing camera head <b>70</b> position data and for correlating the image and position data, such as in an inspection data set.

One exemplary camera head position sensing system shown in <figref idref="DRAWINGS">FIG. 3</figref> is a remote tether insertion depth sensing system including tether markers or sensors <b>64</b> that are arrayed along the tether length and a transceiver <b>84</b> (e.g., an electromagnetic inductive or capacitive sensor coil or RFID sensor) that is coupled in proximity to a rotating machine cavity <b>50</b>/<b>52</b>. The transceiver <b>84</b> detects the markers <b>64</b>, which are correlated to the insertion length L of the tether <b>62</b> within the cavity <b>50</b>/<b>52</b>. Tether <b>62</b> insertion length L becomes one parameter used by the controller for correlating a detected marker with inferred camera head 3D position.

Another exemplary camera head position sensing system shown in <figref idref="DRAWINGS">FIG. 3</figref> is a contactless remote position tracking system, which includes a wireless positioning transmitter <b>78</b> that is coupled to the camera head <b>70</b>, for transmitting a positional signal and at least one wireless positioning system receiver/controller that is coupled to the controller <b>82</b>, for receiving the positional signal, locating the positioning transmitter's 3D position and correlating the positioning transmitter's located position with inferred camera head 3D position. The contactless remote position tracking system shown in <figref idref="DRAWINGS">FIG. 3</figref> has three receivers <b>88</b>A, <b>88</b>B and <b>88</b>C that are coupled to a wireless positioning system controller <b>86</b>. Together the receivers/controller system triangulate the transmitter <b>78</b> position in three dimensions within the turbine <b>30</b> internal cavity and generate camera head <b>70</b> position data that are used by the controller <b>80</b>, along with the image data to in turn generate the inspection data. While separate inspection system controller <b>80</b> and position tracking system controller <b>86</b> are shown as separate devices in <figref idref="DRAWINGS">FIG. 3</figref>, their functions may be consolidated in or further distributed to other known types of industrial controller or general computing devices, such as personal computers or tablet computers.

Optionally the inspection system controller <b>82</b> is in communication with one or more inspection data storage devices <b>90</b> or one or more human machine interfaces (HMI) <b>92</b>. Optionally the controller is in communication with other inspection systems or remote data storage systems via a data bus <b>94</b> or other known communications pathway.

The inspection system embodiment of <figref idref="DRAWINGS">FIG. 4</figref> also incorporates designated waypoint marking recognition capability, such as by placement of indicia markings <b>49</b> within the engine <b>30</b> that are imaged by the camera system in the camera head <b>70</b>. Orientation and size of the indicia markings <b>49</b> in the camera FOV captured images are used by the inspection system to infer orientation of the camera head and optionally to corroborate correlation of image and camera position data acquired from other inferred camera head positioning system embodiments. Inspection data sets acquired by one camera head positioning system embodiment can be compared with a known, control data set obtained by waypoint marking orientation/size observation or a prior mapping of camera head positions within the turbine engine <b>30</b>.

<figref idref="DRAWINGS">FIG. 5</figref> shows an exemplary camera head <b>70</b> that includes first and second optical cameras <b>72</b>, <b>74</b> having fields of view (FOV). The camera head <b>70</b> is configured to house camera head position sensing system components, such as the wireless position transmitter <b>78</b> that was previously described. Another alternative embodiment of a camera head position sensing system incorporates an accelerometer <b>76</b> with an inertial sensor, for correlating camera head movement with inferred camera head 3D position. Various configurations of camera heads <b>70</b> are shown and described in the aforementioned United States patent application publications numbers 2013/0335530 and 2013/0192353. The camera head <b>70</b> is selectively coupled to the tether <b>62</b> and different configurations of camera heads may be substituted for different types of machinery inspections.

Other camera head position sensing embodiments, which incorporate tether <b>62</b> flexure sensing systems for correlating sensed tether flexure with inferred camera head 3D position, are shown in <b>6</b>-<b>9</b>. In <figref idref="DRAWINGS">FIGS. 6 and 8</figref> a sensing array of discrete sensors <b>64</b> are oriented radially and axially about or embedded within an outer skin of the tether <b>62</b>. As shown in <figref idref="DRAWINGS">FIG. 8</figref>, axially and radially aligned rows of sensors, such as sensors <b>6411</b>-<b>641</b>N are coupled by a common sensor data lead <b>651</b> and an opposed pair of equally spaced sensors <b>6421</b>-<b>642</b>N are coupled by a common sensor data lead <b>652</b>. Sensors <b>64</b>XX along a lead are spaced axially at distance Z_X, where X is an integer from 1−N. Comparing <figref idref="DRAWINGS">FIGS. 8 and 9</figref>, tether <b>62</b> flexure changes distance ΔZ between sensor pairs. Sensed change in distance ΔZ is correlated with tether <b>62</b> flexure, as is denoted by the angular references θN. Tether <b>62</b> flexure shape is in turn correlated with the camera head <b>70</b> 3D orientation within the turbine engine <b>30</b> internal cavity. In <figref idref="DRAWINGS">FIG. 7</figref> the sensor array <b>64</b>′/<b>65</b>′ in the camera scope <b>60</b>′ is oriented helically about or within the tether <b>62</b>′.

In some embodiments the tether sensors <b>64</b>/<b>64</b>′ comprise magnetic or capacitance proximity sensors that correlate change in proximity between sensors with tether flexure, as shown in <figref idref="DRAWINGS">FIGS. 6-9</figref>. Alternatively the sensor array <b>64</b> may comprise an optical position and/or shape sensing system that determines changes in optical length of a multi-core optical fiber, such as referred to in United States patent application publication number 2011/0109898.

Although various embodiments that incorporate the teachings of the present invention have been shown and described in detail herein, those skilled in the art can readily devise many other varied embodiments that still incorporate these teachings. The invention is not limited in its application to the exemplary embodiment details of construction and the arrangement of components set forth in the description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.